Manufactured components are generally produced to a size with small variations within an acceptable tolerance limit. When fabricating such individual components together into a multi-part structural assembly, such as an aircraft wing, small clashes between the components (interference fits) or gaps (clearance fits) can occur. In the case of an interference fit, material has to be removed from one or both of the components whilst retaining sufficient structural integrity. For clearance fits, several options are available for filling the gap depending upon its magnitude. For small gaps a liquid spacer which hardens can be used. However, for gaps which are greater than the limits allowed for liquid shimming, it is necessary to insert a hard packer. If the packer merely fills the gap between the components and there is no fixing to either component then there is a limit to the thickness of the gap that can be filled before the presence of the thick packer begins to compromise the structural integrity of the joint. Fatigue cycling and material creep in service can compromise the integrity of the joint.
One shim is known from U.S. Pat. No. 5,815,992 which comprises two parts and which is adjustable in height.
Another shim is shown in U.S. Pat. No. 6,230,446. That shim comprises a wedge shaped shim which is pre-scored to enable easy breaking off and which has a series of recesses on the underside thereof to resist sliding.
Neither arrangement determines the surface profile of the structural element or elements against which the shim is to be located.